I. Field
The following description relates generally to wireless communications and more particularly to handoff to a multi-radio access technology target system.
II. Background
Wireless communication systems are widely deployed to provide various types of communication content, such as voice, data, video, and so forth, and to communicate information regardless of where a user is located (e.g., inside or outside a structure) and whether a user is stationary or moving (e.g., in a vehicle, walking). These systems may be multiple-access systems capable of supporting communication with multiple users by sharing the available systems resources (e.g., bandwidth and transmit power). Multiple-access systems include Frequency Division Multiple Access (FDMA) systems, Time Division Multiple Access (TDMA) systems, Code Division Multiple Access (CDMA) systems, Orthogonal Frequency Division Multiple Access (OFDMA) systems, Third Generation Partnership Project (3GPP) Long Term Evolution (LTE) systems, and others.
Generally, wireless multiple-access communication systems can simultaneously support communication for multiple mobile devices. Each mobile device can communicate with one or more base stations through transmissions on forward and reverse links. The forward link (or downlink) refers to the communication link from base stations to mobile devices. The reverse link (or uplink) refers to the communication link from mobile devices to base stations. These communication links can be established through single-input-single-output (SISO) systems, multiple-input-single-output (MISO) systems, multiple-input-multiple-output (MIMO) systems, and so forth. In addition, mobile devices can communicate with other mobile devices (and/or base stations with other base stations) in peer-to-peer wireless network configurations.
As a mobile device is moved from one geographic area to another geographic area, the mobile device might need to be handed off from a source network to a target network. Many times, both source network and target network utilize a single radio access technology, and, therefore, there is a one-to-one relationship with respect to the handoff. However, there might be times when target network supports a multi-radio access technology and handoff messages related to each radio access technology might be received at different times or one or more handoff messages might not be received. Thus, there is a need to coordinate handoff to a target system that supports multiple radio access technologies.